In an engine-powered automotive vehicle, liquid fuel for the engine is stored in one or more on-board fuel tanks. When the vehicle engine is running, fuel is conveyed from a tank through fuel supply line tubing to the engine fuel system where it is ultimately vaporized into a combustible charge that is combusted in the engine combustion chambers. In certain vehicle fuel systems, such as fuel injection systems, fuel return line tubing may be present to return excess fuel from the engine to a fuel tank.
Because a fuel tank is typically remote from an engine compartment of a vehicle, fuel lines must usually "snake" through available open space between a tank and the engine. Current industry practices utilize metal tubing, steel for example, for such fuel lines. A fuel line tube may comprise a particular geometry that includes multiple bends designed for fitting the tube to a particular installation in a particular vehicle. Such bends should not be so severe as to create restrictions that could impair desired fuel flow through the tube.
In order to provide for fluid-tight connection of fuel line tubing to other fuel system components, the ends of a length of metal tubing may have particular shapes, and the tubes may contain particular connector fittings for mating connection to such other components. For example, a connector fitting, such as an annular connecting nut for example, may be placed on a length of tubing so as to present an internal thread for attaching to a complementary thread of a mating part. A sleeve may be placed over the tube end distal to the connecting nut, and the distal end of the tube may be slightly flared, to provide a fluid-tight seal when the nut is threaded onto a mating part and tightened, drawing the tubing into fluid-tight connection with the mating part.
For assembly convenience, it is known to provide a fuel line tube assembly that comprises a nominally circular walled tube formed to a desired geometry and a connector fitting at one or both ends of the tube. The fuel line tube assembly is disposed in its intended installation location, and its connector fitting(s) are connected to mating components.
A connecting nut fitting that has a circular opening larger than the outside diameter (O.D.) of a circular walled tube on which it is disposed can slide along the length of the circular walled tube. Such a condition may pose a problem for installation of a fuel line tube assembly. For example, if a fuel line tube is relatively long and a connecting nut that is to connect one end of the tube to a mating component has slid to the opposite end, an installer may encounter difficulty, frustration, and even impossibility in sliding the nut back to the proper end. If such a condition happens after the fuel line tube assembly has been placed in its installation position, but before its connection to mating components, the problem may be even more severe. An installation where some or all of the length of a fuel line tube is generally vertical may be especially susceptible to this type of problem.
Accordingly, one general objective of the present invention is to provide a novel fuel line tube assembly that can eliminate problems of this type. A significant advantage of the invention is the provision of a solution that does not add additional parts to a fuel line tube assembly, and that does not create restrictions that might otherwise impair desired fuel flow through the tubing.
In one general aspect, the invention relates to an assembly comprising a length of drawn seamless metal tube and an annular fitting comprising a hole through which the tube passes, the tube comprising consecutive first, second, and third segments that are of substantially identical wall thickness throughout, the first and third segments comprising transverse cross sections that allow the fitting to travel along the respective lengths thereof, and the second segment comprising a transverse cross section that disallows travel of the fitting from one of the first and third segments, along the second segment, to the other of the first and third segments.
In another general aspect, the invention relates to a fuel line assembly for a fuel system of a fuel-consuming engine comprising a length of drawn seamless metal tube, an annular connecting fitting disposed on the tube proximate a terminus of the tube for making connection of an end of the tube containing the terminus to a mating component of the fuel system, the tube comprising consecutive first, second, and third segments that are of substantially identical wall thickness throughout, the first and third segments comprising transverse cross sections that allow the fitting to travel along the respective lengths thereof, and the second segment comprising a transverse cross section that disallows travel of the fitting from one of the first and third segments, along the second segment, to the other of the first and third segments.
In still another general aspect, the invention relates to a fuel line assembly for a fuel system of a fuel- consuming engine comprising a length of drawn seamless metal tube, an annular connecting fitting disposed on the tube proximate a terminus of the tube for making connection of an end of the tube containing the terminus to a mating component of the fuel system, the tube comprising consecutive first, second, and third segments that are of substantially identical wall thickness throughout, the first and third segments comprising substantially identical circular transverse cross sections that allow the fitting to travel along the respective lengths thereof, and the second segment comprising an oval transverse cross section that disallows travel of the fitting from one of the first and third segments, along the second segment, to the other of the first and third segments.
In still another general aspect, the invention relates to a method of making a fuel line assembly which comprises providing a length of nominally circular walled drawn seamless metal tube having substantially identical wall thickness and outside diameter throughout, providing an annular connecting fitting having an inside diameter that allows the fitting to be slid onto the tubing over the outside diameter of the tubing, sliding the connecting fitting onto the tube between a terminus of the tube and a segment of the tube spaced from the terminus of the tube, and re-forming at least a portion of that segment to a non-circular transverse cross section that provides an interference which prevents the fitting from sliding past that segment.
The foregoing, along with further features and advantages of the invention, will be seen in the following disclosure of a presently preferred embodiment of the invention depicting the best mode contemplated at this time for carrying out the invention. This specification includes drawings, now briefly described as follows.